This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Prairie rattlesnakes, Crotalus viridis, are one of the most wide-ranging rattlesnakes in the world and are amongst the most wide-ranging of all venomous snakes. They are found from southern Alberta, Canada, throughout the western Great Plains and east slope of the Rocky Mountains southwards to northern Mexico. They are exposed to a wide variety of ecological situations and are likely to show high geographic variability in prey. We assume therefore that the composition of their venom should vary from site to site and that this variation could be elucidated by fractionating venom collected from snakes across their range. They also show high fidelity to densites and should therefore have relatively high amongst-population genetic variation. We initiated a pilot project in the summer of 2009, the purpose of which was to sequence DNA from a number of snakes and to discover whether we could successfully fractionate their venom. We collected blood and venom from snakes from some localities to investigate genetic variation amongst localities and variation in snake venom proteins amongst these localities. We were successful in sequencing DNA and in fractionating venom components but were hampered in our collection efforts by the cold summer experienced in much of the Great Plains in 2009. We did not sample enough populations, in our opinion, to draw robust conclusions but we are confident that our laboratory techniques work. This is of note because we are not familiar with any other labs that are studying variation in snake venom components.